Surviving the Extremes: A Doctor's Journey to the Limits of Human Endurance (45 page)

Pain can and will break through to the conscious level if behavior needs to be altered to improve the odds of survival. If the incoming data is way outside the body’s safe range, the thalamus will automatically split the input, diverting one signal to the motor cortex for an instantaneous protective response while sending a second signal to the frontal lobe to produce a more modulated but slower response. Your first impulse upon handling a hot cup of tea that is burning your fingers might be to drop it. Your second impulse, which factors in environmental conditions and acquired knowledge, might be to hold on to it, since spilling it will ruin the rug your wife just bought, which on balance might be more risky for your survival than a burned fingertip.

Culture, upbringing, and environmental conditions will wire the frontal lobe in a unique pattern that determines an individual’s response to extreme stress. Nothing will raise your pain threshold and focus your frontal lobes more than a life in the jungle. That’s why
Hermanigildo, after slicing his wrist with a bad swing of his machete, could remain calm even though his pain receptors were firing wildly. His eyes were receiving and transmitting a vivid attention-getting image made fearful and gruesome in the visual cortex by additions from the amygdala. His thalamus was madly processing signals trying to keep order. If the emotion centers were to overload, fear would take over and generate a short-circuit—the coordinated but counterproductive response of panic. The cingulate, already well aware of the problem, chose to ignore the pain readings and sent interference signals to the amygdala to squelch the fear alarm.

Impulses generated in the cingulate have such mastery over the brain that they can easily transform perception into reality. In stressful situations, the cingulate regains control of functions otherwise relegated to the body’s “autopilot”—the autonomic nervous system. Incoming signals from the autonomic nervous system monitor functions such as body temperature and hydration and reach no higher than the brain stem, where they are processed automatically. New signals are then routed back to the effector organs, which make corrections by opening or closing heat-dissipating blood vessels close to the skin, provoking sweating or creating a sensation of thirst. Connections to the conscious mind exist, but they are normally activated only by emotion. Being tempted with a cool drink will increase your thirst; becoming embarrassed—a situation perceived as a threat—will increase blood flow (the basis for blushing); sudden fear will increase perspiration (precooling your body in preparation for action); and being attracted to someone of the opposite sex will make your heart pound. Energizing the cingulate with input from the amygdala is as easy as being controlled by your emotions.

Controlling your body responses with thought is a lot more difficult, but it can be learned. Both the ancient art of yoga and the modern technique of biofeedback teach the conscious brain to regain control of the primitive functions it long since relegated to automatic systems. A brain possessed of such control is able to will the body to respond in a pattern not predicted by the “rules.” Yoga and biofeedback require a great deal of training and practice, but life-and-death exposure to extreme environments seems to facilitate the same sort of
communication along those lost channels. Conscious thought can transmit a response that will favor survival, in effect overriding the dutifully relayed signals from the receptor organs. The mind will thereby create a “reality” that exists only in its imagination but has enough power to command the body to respond in real terms, like soldiers following the orders of a deluded general.

The delusion, as well as the effect, can be subtle, as it was for me in my oppressively hot jungle tent when I misinterpreted a zipper noise as the opening of my tent flap. Soon afterward I felt a cool breeze that didn’t exist but nonetheless lowered my skin temperature and stopped my perspiration. Such subconscious control can cool skin in the jungle or heat it in the mountains, as with the Sherpa who came to my tent after falling through the ice on a subzero day and had warm feet. His cortex had overridden the automatic response to shut down blood flow. It had chosen to sacrifice some body heat in order to preserve the limb.

In higher doses, delusions can have more dramatic effects. As the mind separates further from its true environment, it will override clear sensory warnings and respond dangerously to a reality that doesn’t exist. Victims of severe hypothermia have reported experiencing an overwhelming sensation of warmth. Mixed with confusion and disorientation, it can lead to the phenomenon of “paradoxical undressing.” Climbers or hikers who are freezing to death have been known to take off their clothes just before they collapse. Not understanding this peculiar behavioral pattern, rescuers, and police, often conclude that a lone female hypothermia victim has been raped.

Clearly this sort of behavior runs counter to survival, but so powerful is the brain’s control over the body that at times it seems to be saying, “My mind is made up. Don’t confuse me with the facts.” There is no more blatant example than that which occurs when a hypnotized individual, touched with a pencil at room temperature, is told that it is actually a burning hot poker and subsequently develops a blister.

Thoughts have power. Intensive thinking can amplify, focus, and direct that power enough to effect physical changes both within the body and without. Paralyzed people who are hooked up to amplifiers
can be taught to concentrate their brain waves, creating enough electrical energy to purposefully move a cursor across a computer screen—a dramatic demonstration that willpower is real.

I saw even more convincing evidence in that blinding snowstorm below the summit of Mount Everest. I was sure Beck Weathers had died that day—and maybe he did. Maybe Bernie Chowdhury and Pablo Valencia also died. At the limit of their ordeals, they all had intense visions of being outside their bodies. This kind of sensation would arise if the circuits to the cerebral cortex were shut down in a last-ditch attempt to preserve energy for the basic body maintenance centers in the brain stem. The cortex would no longer receive any outside stimulation. Such internal quiet would lower the threshold of excitation for the nerves, setting off random bursts of impulses. These bursts of electricity can also be triggered by fear, fatigue, low oxygen, and low blood sugar—all common conditions in survival situations. Some of the bursts might excite the temporal lobe, the portion of the cerebral cortex below the temples that controls conceptual thinking and language and image associations. Other impulses might excite the occipital lobe at the back of the head where visual images are registered. The effects could be seeing visions of loved ones or hearing the voice of God—phenomena that survivors often say gave them the strength to go on. With the cortex floating free, the survivor would also undergo that sense of detachment from the body that Beck, Bernie, and Pablo Valencia all said they felt—the out-of-body experience often described by people who “died and came back.”

Though I was certain that it was impossible for Beck to survive, Beck had other ideas. An idea is made from, or at least causes to form, a pulse of electricity in the brain. Fear of dying generates a lot of electricity in the amygdala, the emotion center. Memories of home and family form electrical pulses in the frontal lobes that become more powerful as the images grow more intense. Nerve cells, or neurons, in every brain center connect with cells in every other center via axons, long wirelike offshoots that conduct electricity. Axons end in branches that don’t quite touch any other nerve. They do, however, come very close to hundreds of dendrites, the receptor twigs of other neurons with which the axons nearly intertwine. When the electrical
impulse reaches the end of the axon, it releases a chemical neurotransmitter that floats the signal across the tiny gap, or synapse, between axon and dendrites. The neurotransmitter has the potential to restart the electrical signal in each of the dendrites with which it comes in contact. Each of those receptor neurons can in turn start an impulse in hundreds of other neurons. The 100 billion neurons of the brain produce 100 trillion synaptic connections.

But a chain reaction will not lead to a coordinated response any more than an electrical signal traveling through a ball of uninsulated wires will turn on a machine. Not every thought leads to effective action. A microamp of thought that floats across a synapse won’t react with every dendrite it washes up on. Whether or not a neurotransmitter will reconstitute an electrical signal in the next neuron depends on the reception it receives when it arrives. Memory, learning, experience, and training will modify the response by having previously deposited chemicals that facilitate or inhibit the reconversion to electricity. Furthermore, the firing of the neuron is an all-or-nothing response. Once a threshold level of electrical current is reached, the signal is transmitted. Reaching that level might be achieved by one strong incoming signal, though it often is the additive result of many signals from many axons arriving on the same dendrite. A neuron receiving emotional input from the amygdala might be slightly below the threshold to fire. A small additional boost by a thought arriving from the frontal cortex, however, might put it over the top. The signal generated might induce a nonproductive response such as panic, or it might get channeled and focused to induce survival behavior. One pulse of electricity, properly modulated, can create an electrical and chemical symphony. The modulating thought that provides enough energy to orchestrate that change is willpower. It can stir a body back to life.

Though Beck lay motionless in the snow, there was activity in his brain. Thought signals sparked his nerve cells, creating the random currents of a dreamlike state. Had Beck been hooked up to a PET scanner, it would have indicated energy flowing between the amygdala and frontal lobes as well as to the most primitive centers that maintain heartbeat and breathing. But his circuits were powering down and,
with no new energy sources, would soon have shut off. The PET scan images would fade as Beck drifted into a peaceful predeath unconsciousness.

Beck refused to die, however, and this created a change. Suddenly the weakening signals that were converging on the cingulate, the seat of the will, were amplified and redirected, becoming powerful enough to reinvigorate the parts of his brain that control motion and judgment, the functions he needed for survival. Beck got up out of the snow. He was able to think clearly enough to calculate in which direction to move. He headed off toward his own salvation.

Given that there was no change in his outside environment, where had Beck’s burst of strength come from? How could the signal coming out of the cingulate suddenly be far greater than the sum of the signals that went in? What ignited the spark that pushed his nerves over the threshold? Perhaps it came from some undetectable source of energy within his nerve, or perhaps from a confluence of brain waves whose frequencies suddenly meshed to create an amplitude much greater than that provided by the individual components, much as a resonating sound can be far louder than the sum of the waves that form it. But still, how did Beck start it happening right then?

The laws of physics require a cause for every effect. Progressing backward, you eventually have to reach a first cause—some fundamental source of energy not dependent on anything before it, a primal force, not directly observable but perhaps the most natural and most fundamental of all. In the cosmos, the origin of all energy is called the “singularity,” and the force it generates is called the “big bang.” In the mind, the origin is the cingulate and the force is called will.

The true nature of will remains mysterious. Is it an electrobio-chemical resource hidden deep within the brain or a force instilled from without by a higher power? The electrical spark generated by the cingulate may be the origin of will, or it may be the first detectable result of faith. The answer is within our bodies but beyond our grasp.

Every scientist knows that if you can’t step outside a phenomenon to observe it, you can’t hope to fully understand it. We need to use our brains to analyze our brains, so the information we take in will never be completely objective. Unable to escape from our own brains,
there will always be an impenetrable, mystical barrier to understanding ourselves. The fundamental nature of the human will must remain unknowable. Ultimately, our explanations for surviving the extremes will require not just science, but faith.

JUNGLE

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